There was "no clear evidence" the head was the primary point of contact, Pell adds.
Dowd caught Staal up high in the neutral zone midway through the third period during the Capitals' 6-4 win Thursday night.
The officials handed Dowd a minor penalty for a hit to the head. The Sabres weren't pleased with that decision, with head coach Ralph Krueger saying he's surprised Dowd wasn't given a harsher penalty, and defenseman Jake McCabe calling the incident "pretty dirty."
Staal was deemed day-to-day postgame.
Buffalo landed the veteran pivot in an offseason trade with the Minnesota Wild.